The Linux command line consists of a number of words with optional values.
At present U-Boot allows this to be changed using the bootargs environment
variable.
But this is quite painful, since the command line can be very long.
Add a function which can adjust a single field in the command line, so
that it is easier to make changes before booting.
Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
d07861cc7a